Add alert to test if RDP page JavaScript executes at all

- Added alert('RDP page script is loading!') at the very beginning
- This will show if the script is being executed or blocked
- If no alert appears, the issue is script loading or CSP
- If alert appears but no console logs, there's a JavaScript error

wssshd2/templates/rdp.html

@@ -309,6 +309,7 @@
 </div>
 <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js"></script>
 <script>
+alert('RDP page script is loading!');
 console.log('RDP page script starting...');
 
 // init kbdlayout_input